Association of Clinical Pathologists, Wessex Branch

vascular arrangement is in fact a feature of all human lymph nodes. Our study was designed to reinvestigate this traditional view of lymph nodal vascular supply. The arterial tree supplying lymph nodes from human cadavers was injected with a radio-opaque barium suspension (75%w/v). Superficial lymph nodes from the groin and deep lymph nodes from the small intestinal mesentery were studied by means of specimen radiography and histological examination. Such combined techniques allowed demonstration of the vessels injected, and study of their macoscopic and microscopic distribution. The superficial lymph nodes from 17 subjects all showed that individual nodes were supplied by a single arterial branch which entered the hilum in the manner described by Calvert. By contrast the deep mesenteric lymph nodes, which usually lack a central hilum, were each supplied in all 8 subjects by two to five arteries which impinge upon them radially from several directions, and from different vascular arcades. Such marked differences in the arterial supply of superficial and deep lymph nodes probably reflect microanatomical differences in the two types of lymph node. The radial arterial supply of deep nodes appears related to their vascular trabeculae, the more complex arrangement of cortex and paracortex, and

typical human lymph node is depicted with a central hilum through which pass its arteries, veins and efferent lymphatic channels. Subsequently there has been no formal confirmation as to whether this vascular arrangement is in fact a feature of all human lymph nodes. Our study was designed to reinvestigate this traditional view of lymph nodal vascular supply.
The arterial tree supplying lymph nodes from human cadavers was injected with a radio-opaque barium suspension (75%w/v). Superficial lymph nodes from the groin and deep lymph nodes from the small intestinal mesentery were studied by means of specimen radiography and histological examination.
Such combined techniques allowed demonstration of the vessels injected, and study of their macoscopic and microscopic distribution.
The superficial lymph nodes from 17 subjects all showed that individual nodes were supplied by a single arterial branch which entered the hilum in the manner described by Calvert. By contrast the deep mesenteric lymph nodes, which usually lack a central hilum, were each supplied in all 8 subjects by two to five arteries which impinge upon them radially from several directions, and from different vascular arcades.
Such marked differences in the arterial supply of superficial and deep lymph nodes probably reflect microanatomical differences in the two types of lymph node. The radial arterial supply of deep nodes appears related to their vascular trabeculae, the more complex arrangement of cortex and paracortex, and to functional characteristics which are features of these lymph nodes. Lack of knowledge of the arterial supply of deep lymph nodes in man has led to misconceptions in the understanding of both reactive and pathological conditions affecting these We reported 10 cases of colonic or small intestinal volvulus in which mesenteric lymph nodes were available for histological examination between 1975 and 1983. Lymph nodes displayed frank infarction in 4 of 6 cases in which the bowel showed mucosal necrosis as a result of the volvulus. None of 4 cases of volvulus with entirely viable mucosa showed nodal necrosis. Common to both these groups were lesser lymph nodal ischaemic changes in the form of lymphoidal cell depletion and a distinctive form of capsular hypervascularity. Such lesions were not seen in control patients with a variety of bowel pathology although sinus distention, erythrocyte extravasation and generalised vasodilatation were seen in lymph nodes from cases of volvulus and in other intestinal diseases. No case showed a malignant lymphoma.
Surprisingly this is the first documentation of lymph nodal ischaemia associated with an identifiable vascular lesion causing ischaemic damage in an organ supplied by the same blood vessels. We believe lymph nodal ischaemia to be much more common than is generally realised, and do not feel that the association with malignant lymphoma is as marked as has been suggested.
EXTRAPULMONARY OAT  Monoclonal antibodies have been particularly useful in both the biological characterisation and differential diagnosis of systemic lymphomas, but primary brain lymphomas have not as yet been classified in the same detail as their systemic counterparts. We have therefore examined 10 brain lymphomas with a panel of 10 monoclonal antibodies, including markers for B cells, B cell progenitors, T cells, T cell subsets, myeloid series cells, in addition to routine histology. In 4 of the cases, routine histological techniques were not diagnostic and immunocytochemistry was responsible for making the diagnosis. In the 10 cases of intracranial lymphoid tumour, 8 were shown to be B cell lymphomas with no detectable systemic involvement, one was a myeloid deposit and one a hairy cell leukaemia deposit.
Our findings suggest that primary brain lymphomas are B cell lesions, and their place in the current biological classification of lymphoid malignancies will be discussed, as will the clinical im-

RESULTS
Examination of faeces from 1097 patients with diarrhoea during a one-year survey yielded the results shown in the following Table Sera from 13 patients were tested to see whether agglutination was given with strains of Aeromonas isolated from their own faeces. Two sera gave titres of 1 in 80 and the remainder 1 in 20 or less. Fifty normal control sera from N.B.T.S. were also tested against 18 strains of Aeromonas and 2 of these gave titres of 1 in 40 and the rest 1 in 20 or less. It was concluded that serum agglutination tests did not yield useful diagnostic results.

CONCLUSION AND FUTURE WORK
Our year long study has shown that Aeromonas is a highly significant cause of diarrhoea in U.K. residents as well as in overseas travellers, second only to Campylobacter in frequency. The condition is often a short self-limiting disease but may occasionally cause chronic diarrhoea lasting several months. A serological test would be helpful in assessing the significance of the isolation of Aeromonas from the stools of a patient with chronic diarrhoea. Wadstrom et al. (1976)  Relatively small, cheap, easily used pieces of equipment are now on the market for use in the side ward, Intensive Care Unit, Operating Theatre, and possibly Health Centre. These would enable the clinician to obtain the results of certain tests rapidly, without the necessity of sending blood or urine samples to the Department of Pathology. In particular, blood glucose, plasma P02, PC02, pH, bicarbonate, plasma sodium and potassium, plasma and urine osmolality, haemoglobin, white count and platelet counts, could all be estimated outside the laboratory with apparent accuracy and precision. Problems discussed included: (1) Which budget pays for the initial purchase, increased running costs, maintenance and repairs, if the apparatus is not directly under the control of the Laboratory? (2) Who is responsible for day-to-day maintenance and quality control? (3) Methods of assessment of the 'black box' apparatus in comparison with 'main frame' apparatus in the Laboratory. (4) Who uses the new equipment? Nurses, and/or clinical doctors, and/or technicians, and/or MLSO's  Potassium depletion is known to cause vacuolation of renal tubular cells which is associated with defects in renal tubular function, polyuria and resistance to vasopressin, tubular proteinuria and an increase in the urinary excretion of the lysosomal enzyme N-Acetyl-P-Glucosaminidase (NAG). Potassium depletion also causes an increase in ammonia production by renal tubular cells. The effects of an increase in intracellular ammonia can explain the above changes due to potassium depletion on renal tubular cell function and morphology. Renal immunofluorescence (I.F.) is of proven value to the clinician as a routine procedure in diagnostic renal biopsy. It might also be of value to the pathologist at necropsy in 5 situations: 1. Sudden death with a possible renal cause, e.g. hypertensive cerebral haemorrhage; 2. Some forensic cases, e.g. maternal death with undiagnosed pre-eclampsia; 3. Chronic renal failure without biopsy-proven disease; 4. Follow-up of biopsy-proven renal disease to study natural history and/or the effects of treatment; 5. As a research tool screening for occult renal disease in necropsy series.
To be valid, post-mortem renal I.F. findings must be similarly interpretable to those in life. It must be shown that there is similar uptake of antibodies, that effects due to death itself and to the interval between death and necropsy are negligible or predictable, and that findings after death are congruent with those in a patient's previous biopsies.
Post-mortem renal I.F. was done in 84 cases in Bristol between 1974 and mid-1983, drawn from Southmead Hospital (67), Bristol City Mortuary (16), and Bristol Children's Hospital (1). 1 5 patients had also had at least one renal biopsy with I.F. A standard panel of 5 direct fluorescent antibodies was used, against IgG, IgA, IgM, fibrin/fibrinogen and complement (C3). The interval between biopsies and death ranged from 2 days to just under 4 years, and that between death and necropsy from 2 hours to 5 days. Standard mortuary refrigerators were used for storage.
We found that with immunoglobulins, postmortem renal I.F. findings in a given disease were the same as in life or showed expected progression. The same was true for complement. Death did not by itself cause the deposition of immunoglobulins in kidney. This was less so with complement, there Bristol Medico-Chirurgical Journal January 1984 being some apparent 'false positive' results. The findings for fibrin/fibrinogen were unpredictable and inconsistent.
We therefore conclude that post-mortem renal I.F. is an interpretable, reliable procedure yielding useful and consistent results.